Centralized radio system



Examin ill!!!) E. KRUEGER CENTRALIZED RADIO SYSTEM Filed Oct. 11,

away/ APER/OD/C AA/PL/HER 340/0 RECE/VER' INVENTOR [/7137 MW 6618. 7K

m ATTORNEY TWA ABLE TUA/ABLE RAD/0 Riff/V5? Patented Apr. 13, 1937 UNITED STATES LXammei PATENT OFFICE CENTRALIZED RADIO SYSTEM Ernst Krueger, Berlin,

Germany, assignor to tion of Germany Application October 11,

1934, Serial No. 747,843

In Germany October 10, 1933 3 Claims.

In buildings in which a plurality of broadcast receivers are to be operated on high aerials, serious difiiculties arise because of the fact that the various antennae are coupled with one another. These difficulties may be circumvented by what is known as a common or joint antenna which operates upon an aperiodic radio frequency amplifier. The amplified energy at radio frequencies is thereupon fed to the various receiving points located in the different rooms of the building through high frequency cables.

In the case of installations of this kind the demand is made that the amplifier should be operative only if at least one receiver is in circuit. Inasmuch as no modifications or alterations should be made necessary in the commercial and standard type of set it has so far been possible to insure automatic connection only by means of using a time switch. In order to control and actuate the aperiodic amplifier from a remote point recourse could be had to a relay in combination with the amplifier. However, this relay would have to be operated from each receiver by distinct control means. Hence, what has so far been feasible was automatic actuation and control of the amplifier, but no tele-control or switching; or else remote control, but no automatic control and switch action.

The solution of the problem connected therewith according to the invention is insured by the use of relays with the receivers which are included in the power supply-line or battery leads of each receiver set. This relay serves to control an additional relay connected in the power supply-line (mains) or battery connection near the aperiodic amplifier. The relays used near the receiver sets are suitably designed as adapters. The adapter is plugged into the mains socket and the mains connecter plug of the receiver is introduced into the adapter. It, then, the radio receiver is switched in, a contact will be closed in the relay by action of the current which is caused to fiow through the receiver.

As a result the relay combined with or mounted near the amplifier is rendered operative and the amplifier is energized or switched in. If additional receiver sets are switched in, the contacts in the adapter connected relays will be closed also in these. It is only when the last receiver has been disconnected that the relay associated with the amplifier will be automatically opened again.

A circuit diagram oi. an installation comprising a joint aerial according to this invention is shown in the accompanying drawing. Referring to the same, I denotes the antenna which is coupled to the radio frequency amplifier 2. The output circuit of this aperiodic amplifier is coupled with the radio frequency transmission cable which consists of an inner conductor 3 with a metallic enclosing sheath or envelope 4 and insulated therefrom. In the mains connection or power supply leads N of the amplifier is included the switch contact 5 of a relay whose coil 6 with a source of current I, a control lead I, a number of paralleled switch contacts 8 corresponding to the number of receivers, and the envelope 4 of the radio frequency distributor cable forms one circuit. The switch contacts 8 are actuated by means of relay coils 9 which are included in the power supply or 'the battery leads l5 of the various radio receiver sets It. Each receiver has an on-ofi switch l6 inits supply circuit, the operation of which causes the circuits of the receiver to be energized in the usual manner.

Inasmuch as the several receivers consume different amounts of current, it will be necessary to adapt the similar relay solenoids 9 to the consumption of current of each receiver. This preferably is accomplished by a resistance ll connected in parallel to the relay coil dimensioned so as to suit the amount of current of the particular receiver and thereby cause each of coils 9 to pass the same amount of current.

The relay adapter plug may also be provided with an optical or visual signal or indicator means so. that there will be a check-up on the starting of operations of the amplifier at the location of the receiver set.

If it is desired that a distinct or separate control lead I shall be dispensed with, then the inner conductor 3 of the transmission line could be used as a relay control lead. But in that case the control d. 0. must be shut off from the amplifier output circuit as well as from the cable end, while the lead to the relay must be blocked both for radio and audio frequency currents.

I claim:

1. In a radio frequency distribution system, the combination of an aperiodic amplifier, an antenna coupled to the input of said amplifier, means for energizing said amplifier including a relay, a plurality of radio receivers located at points remote from said amplifier, a current energizing circuit connected to each of said receivers, a radio frequency transmission line connected to the output terminals of said amplifier and the input terminals of each of said receivers, switch means located at each of said receivers for operating said relay and a relay coil connected in series in the current energizing circuit of each of said receivers arranged to actuate said switch means in response to the passage of current through said energizing circuit.

2. In a radio frequency distribution system, the combination of an amplifier, an antenna coupled to the input of said amplifier, an energizing circuit for said amplifier including a relay, a radio frequency transmission line connected to the output terminals of said amplifier and extending to a plurality of remote points, a radio receiver tunable to a desired signal frequency connected to said transmission line at each of said points, a power supply circuit including a. switch for each of said receivers and means operated by the closure of any one of said switches arranged to energize the winding of said relay.

3. In a radio frequency distribution system, the

Espenschied et a1 British patent Hopkins Grouse Davis combination of an amplifier, an antenna coupled to the input of said amplifier, an energizing circuit for said amplifier including a relay, a radio frequency transmission line connected to the output terminals of said amplifier and extending to a plurality of remote points, a radio receiver tunable to a desired signal frequency connected to said transmission line at at least two of said points, a switch at each 01' said receivers, circuits connecting said switches to said relay; an energizing circuit, including a relay arranged to actuate one of said switches, connected to energize each of said receivers and means to equalize the currents through said last named relays upon the passing of currents of different amounts through said energizing circuits.

ERNST KRUEGER. 

